1. Field of the Invention
The present invention relates to heat-shrinkable, tubular foams useful as thermal insulators, cushioning materials, and the like for various pipes, hoses, etc. and to a process for producing such tubular foams.
2. Description of the Related Art
Covering or jacketing various pipes, hoses, etc. with tubular EPDM foams has so far been practiced extensively for thermal insulation and protection purposes, but there has been no tubular foam having a heat shrinkability. Conventionally, covering of a pipe, hoses, or the like with a tubular foam has been carried out by; a method comprising applying a lubricant on the outside of a pipe, hoses, or the like and/or on the inside of a tubular foam and then pushing the pipe, hoses, or the like into the tubular foam; a method comprising inflating a tubular foam by applying pressure and then pushing a pipe, hoses, or the like into the inflated tubular foam; or a method comprising cutting a tubular foam lengthwise to open it and inserting and fixing a pipe, hoses, or the like in the tubular foam by winding a tape around the foam.
On the other hand, JP-A-58-51121 proposes heat-shrinkable sheets produced from an ethylene-.alpha.-olefin copolymer or an ethylene-.alpha.-olefin-polyene copolymer, wherein the .alpha.-olefin refers to the .alpha.-olefin having 4 or more carbon atoms.
Conventional methods for inserting pipes, hoses, or the like into tubular ethylene-.alpha.-olefin-nonconjugated diene copolymer foams involve various problems such as the entry of lubricant into pipes, hoses, or the like, the low efficiency of the foam pressurizing and inflating operation and of the inserting operation, and the rupture of tubular foam caused by pressure application. Accordingly, there has been desired a safety and high-efficiency method for the covering.
It is an object of the present invention to provide an improved method for covering pipes, hoses, and the like with tubular foams based on an ethylene-.alpha.-olefin-nonconjugated diene copolymer.
Other objects and advantages of the present invention will be apparent from the following description.